Giant Kirby is fought on Stage 5 of Adventure Mode upon the Green Greensstage as an optional boss. If the player manages to defeat all of the Kirbys (including the first one who fights alone) in 31 seconds or less, a cinematic will play where Giant Kirby drops onto the second floating platform and lands crouching before standing up and smiling.

Giant Kirby is slightly larger than a regular Kirby with a Super Mushroom and is heavier and stronger than Kirby. If the player defeats Giant Kirby, they will receive the bonusGiant Kirby KO, which awards 10,000 extra points.